This invention relates to a control apparatus for a multiple-axis machine tool having a plurality of movable components each shiftable by a respective linear drive along a respective translation axis or rotatable by a respective rotary drive about a respective rotation axis. The control apparatus functions to control the motion of the machine tool components along the translation axes and about the rotation axes.
In a control apparatus of conventional type, the motions of the machine tool parts are controlled in accordance with predetermined programs corresponding to the various movable machine tool parts. The actual position or orientation of a movable machine tool component with respect to a particular axis is determined by a position setting device associated with that axis. The desired position or orientation of a machine tool component and the actual position or orientation thereof with respect to a particular axis are fed to at least one position controller which generates a control signal encoding the value of a desired rate of translation or rotation, this control signal being transmitted to the drive associated with the respective axis.
With the increasing degree of automation, modern machine tools have an increasingly larger number of axes along which or about which machine tool components move. For example, modern lathes are equiped with two independent slides. In addition, the movement of the headstock and the loading and unloading of the machine may be controlled by the machine tool control apparatus.
To ensure accurate positioning of each movable machine tool component with respect to its associated axis or axes, the control apparatus of the above-mentioned type is designed so that the actual positions of the particular machine tool component relative to its axes are controlled with respect to associated predetermined reference positions. The controlling functions are executed by a common position controller. Inasmuch as, depending on the application, different dynamic behaviors are required of such a position controller (a simple milling or drilling machine is adequately controlled with a position control cycle of 8-10 msec, while a highly dynamic lathe requires cycle times of approximately 1-4 msec) the design of the position controller must frequently be adapted to the particular application.
An object of the present invention is to provide an improved machine tool control apparatus of the above-described type.
Another, more particular, object of the present invention is to provide such a control apparatus which is easily and simply adaptable to different technical applications.